#include <stdio.h>
#include <ctype.h>
#include "lt_string.h"

int to_lower_case(char *str)
{
	if ( str == NULL )
	{
		return -1;
	}
	while ( *str != '\0' )
	{
		*str = tolower(*str);
		str++;
	}
	return 0;
}